Method of producing flat or surface commutator



1968 TERUMOTO YAMAGUCHI ETA!- 3,414,970

METHOD OF PRODUCING FLAT OR SURFACE COMMUTATOR Filed July 11, 1966 mb HMNUA O s -MT n I O mMM AME 0 WM DN A M UE mww TKH UJ Y B United StatesPatent 3,414,970 METHOD OF PRODUCING FLAT OR SURFACE COMMUTATOR TerumotoYamaguchi, Anjo-shi, Kisuo Kawamoto, Nagoya-ski, and Hideo Amemiya,Hekikai-gun, Aichi-ken, Japan, assignors to Nippon Denso KabushikiKaisha, Kariya-shi, Aichi-ken, Japan Filed July 11, 1966, Ser. No.564,377 1 Claim. (Cl. 29-597) The present invention relates to a flat orsurface commuator in an electric machine wherein the surfaces where thebrushes make contact with each of commutator bars are contained in aplane which is perpendicular to the axis of rotation.

PRIOR ART In the prior art the flat or surface commutator of the typedescribed above has been manufactured by cold forging a hollow tubularblank so as to provide directly pawls extending toward the back surfaceof the commutator; or by forming a tubular blank whose axial section isof reversed U-shaped and providing pawls by dividing the tubular portionof said tubular portion by means of milling, broaching machining, etc.However, according to the above mentioned prior art methods, it is verydifficult to manufacture a commutator of a small capacity whosethickness of pawl is rather thin and whose length of the pawls arerather longer.

Known is another method in which a plate blank is subjected to press atthe center thereof so as to form a cylindrical projection whose one endis closed or blinded, then the outer periphery of the flat plate portionthereof is cut off so that a disk like flange whose center is that ofsaid cylindrical projection may be formed and at the same time a groupof projection are formed along the outer periphery thereof, saidprojections are bent toward the back surface of the disk so as to formpawls of the outer periphery; and the closed or blind portion of thecylindrical projection is cut off so as to separate the remainderthereof by broaching in the axial direction thereof in order to formpawls around the inner periphery. However, according to the lastmentioned prior art method the economy of the material is verydisadvantageous and it is difficult to produce a cylindrical projectionwhose one end is closed or blinded by press work especially when thepawls of the inner periphery are thin and long.

THE INVENTION Bearing in mind the above stated disadvantages encounteredin the prior art methods, the primary object of the present invention isto eliminate such disadvantages and to provide a method formanufacturing a commutator having rather thinner and longer pawls with abetter economy of the raw material thereof from a tubular blank byforming a disk type flange wherein a portion thereof is madeperpendicular to the axis thereof leaving a part thereof as it is andfurther by extending the tubular portion left unchanged in the axialdirection thereof by passing therethrough a steel ball, etc.

The invention will be described with reference to the accompanyingdrawing illustrating the steps of a method according to the invention inthe order to be mentioned, wherein;

FIG. 1 is a longitudinal view of a cylindrical or tubular blank;

FIG. 2 is a longitudinal sectional view of the first step semi-finishedproduct which has been pressed from said cylindrical or tubular blank;

FIG. 3 is a longitudinal sectional view of the second step semi-finishedproduct;

FIG. 4 is a front view of the third step semi-finished product;

FIG. 5 is a sectional view taken along the line A-A oi FIG. 4; and

FIG. 6 is a longitudinal sectional view of a finished commutator.

In the figures, 1 is a cylindrical or tubular blank of a a suitableconductive material such as copper having a predetermined wall thicknessand length. The substantial part of cylindrical or tubular blank 1 isformed by press work into a disk like flange 3, as shown in FIG. 3,having a predetermined wall thickness and outer diameter and beingperpendicular to the axial direction thereof, leaving a part of thecylindrical or tubllar portion 2 as it is. That is the first stepsemi-finished product, Thereafter, the cylindrical portion 2 of thefirst step portion 2 is, as illustrated in FIG. 3, fitted into asupporting table 4 having an inner diameter substantially equal to theouter diameter of the cylindrical or tubular portion and is applied witha steel ball 5 having an outer diameter suflicient to form a desiredwall thickness of the tubular portion 2. Thus the cylindrical or tubularportion 6 extending axially thereof and having a wall thickness thinnerthan that of the cylindrical or tubular portion 2 is produced and thisis the second step semi-finished product. Then as shown in FIGS. 4 and5, the second step semi-finished product is blanked so as to form apredetermined number of slots 7 having a predetermined depth and widtharound the outer periphery of the disk like flange 3, providing aplurality of projections 8. Next, by broaching a plurality of slots 9whose number is equal to that of the slots 7 provided at the outerperiphery and whose center lines are so arranged as to coincide withthose of corresponding slots 7 of the outer periphery are provided, thusforming a corresponding number of projections 10. The third stepsemifinished product thus obtained is so processed, as ill-ustrated inFIG. 6, as to bend each of the outer peripheral projections 8 toward theback surface of the semi-finished product, and further to the radialdirection thereof, thus forming a pawl 11. Each of the inner peripheryprojections 11 is slightly bent outwardly radially so as to form a pawl12. Such processed product is further processed so that a metallic bush13 is located in this skelton structure and further an insulatingmaterial is molded around this semi-finished product whereby said pawls11 and 12 are completely embedded therein. Further, slots 15 forconnecting the windings of an armature are provided and also grooves 16are provided along the center lines of the slots 7 and 9 so as toseparate each commutator segment havtion in minor details, materials andproportions other portions thereof respectively.

The essential features of the invention has been described in thisspecification without restricting the invention in minor details,materials and proportions other than by the scope of the followingclaim.

What is claimed is:

1. A method for manufacturing a flat or surface commutator characterizedby forming a portion of a cylindrical or tubular blank having a suitableor appropriate wall thickness and length into a disk like flange leavingthe remaining portion of said blank as it is; extending the remainingportion of the cylindrical or tubular blank in the axial directionthereof by passing a steel ball through the inner portion thereof; thenproviding a plurality of slots around both said cylindrical or tubularportion and the outer periphery of said disk link flange, each of saidslots in the tubular portion being aligned with and having acorresponding slot in the flange portion; bending thus formedprojections so as to form pawls; molding an insulating material aroundthe remaining portion so as to embed said pawls; and separating eachsegment by providing a groove or recess along each of the center linesof said corresponding slots in the flange and tubular portions.

References Cited UNITED STATES PATENTS 1,901,955 3/1933 Giaimo 29--5972,421,845 6/1947- Moeller 29597 X 2,945,971 7/1960 Apostoleris 310235 XUS. Cl. X.R.

1. A METHOD FOR MANUFACTURING A FLAT OR SURFACE COMMUTATOR CHARACTERIZEDBY FORMING A PORTION OF A CYLINDRICAL OR TUBULAR BLANK HAVING A SUITABLEOR APPROPRIATE WALL THICKNESS AND LENGTH INTO A DISK LIKE FLANGE LEAVINGTHE REMAINING PORTION OF SAID BLANK AS IT IS; EXTENDING THE REMAININGPORTION OF THE CYLINDRICAL OR TUBULAR BLANK IN THE AXIAL DIRECTIONTHEREOF BY PASSING A STEEL BALL THROUGH THE INNER PORTION THEREOF; THENPROVIDING A PLURALITY OF SLOTS AROUND BOTH SAID CYLINDRICAL OR TUBULARPORTION SAID THE OUTER PERIPHERY OF SAID DISK LINK FLANGE, EACH OF SAIDSLOTS IN THE TUBULAR PORTION BEING ALIGNED WITH AND HAVING ACORRESPONDING SLOT IN THE FLANGE PORTION; BENDING THUS FORMEDPROJECTIONS SO AS TO FORM PAWLS; MOLDING AN INSULATING MATERIAL AROUNDTHE REMAINING PORTION SO AS TO EMBED SAID PAWLS; AND SEPARATING EACHSEGMENT BY PROVIDING A GROOVE OR RECESS ALONG EACH OF THE CENTER LINESOF SAID CORRESPONDING SLOTS IN THE FLANGE AND TUBULAR PORTIONS.